Geng Weiwei

Nanjing University of Science and Technology | NJUST · Department of Electrical Engineering College of Automation Engineering

In this paper, the stator cooling system of an axial flux permanent magnet (AFPM) motor with integer-slot distributed winding (ISDW) for high speed high power electric vehicle traction application is discussed. The aim of the research is quantitively figuring out the power /power density boundaries of this type of axial field PM motor with the adop...

Due to the high-power density and compact structure, axial-flux permanent magnet (AFPM) machines have gradually received much attention with a view to researching breakthroughs in the next generation electric drive technology for electric vehicles in the recent decades. The AFPM machines with factional slot concentrated winding (FSCW) and yokeless...

A new spoke-type interior permanent magnet (IPM) machine with enhanced flux-concentrating capability and high saliency ratio rotor is proposed for the extended-range electric vehicles traction applications. The evolution of the proposed flux-concentrating rotor structure from the spoke-type IPM rotor is illustrated to achieve a higher saliency rati...

In this article, a new spoke-type interior permanent magnet (PM) with a flux-concentrating rotor is proposed. Based on the flux-concentrating principle, the fitting parameters between PMs and magnetic cores on the rotor make a significant impact on the flux concentration and saliency effect, thus resulting in the output torque and power capacity. T...

This paper focuses on the temperature rise of high-speed disc rotor considering the air-friction loss for an axial flux permanent magnet (AFPM) motor with double rotors and sandwiched stator. The air-friction loss and the heat transfer coefficient on the rotor surface at different speed are obtained based on the formula method and Fluid-Thermal cou...

This paper presents a new interior permanent magnet (IPM) rotor structure/ assembly which inherits from the Halbach magnet configuration and spoke-type IPM rotor to achieve a high saliency ratio and high torque/power density. A higher air-gap flux density and a higher saliency ratio are expected to improve torque density, while the rotor inner diam...

Due to the larger diameter of effective air-gap for torque production, outer-rotor permanent magnet (PM) machines exhibit the distinctive advantages, such as high torque density and large rotor inertia. This article presents a compact outer-rotor permanent magnet starter/generator (OR-PM S/G) to match diesel engine for extended-range hybrid electri...

In order to solve the problems of poor capacity and unsatisfactory efficiency of flux-weakening control for the axial-flux permanent magnet (AFPM) machines with surface-mounted PM rotor structure, a new axial-flux hybrid-excitation machine with double consequent-pole rotors is proposed, which combines the high torque density of the AFPM machine and...

This paper employs grain-oriented (GO) silicon steel in an axial-flux permanent magnet (AFPM) machine to improve its torque and efficiency. Rolling direction of the GO material have been studied to ensure the machine’s main magnetic flux passes through the easy magnetization direction. Based on the study of the electromagnetic characteristics of AF...

Ironless stator axial-flux permanent magnet (PM) machines are becoming a promising choice in aerospace and automotive applications. However, they come with the characteristic of extremely small armature inductance, which will result in a challenging difficulty to drive with the conventional inverter. Considering the limitation on increasing the swi...

In this article, the implementation of a single-stator double-rotor fractional-slot concentrated-winding (FSCW) axial-flux permanent-magnet machine is presented to verify a simple and reliable structure design and oil-immersed cooling of the stator with modular soft magnetic composites (SMC) core. Due to the yokeless and segmented stator, the proce...

Ironless stator axial-flux permanent magnet (AFPM) machines provide many attractive electromagnetic performances such as high efficiency in high-frequency mode and strong short-term overload ability, which make them more competitive in flywheel energy storage applications. However, designing high-torque-density AFPM machines, particularly their iro...

Outer‐rotor permanent‐magnet (OR‐PM) machines provide several distinct advantages such as high torque density and large rotor inertia due to the large outer diameter of effective air gap for power conversion. The purpose of this study is to replace flywheel with the outer rotor by adopting OR‐PM machines since this topology is well‐suited for integ...

Due to the elimination of the magnetic core on the stator, the design of coils is more flexible and more sensitive to the number of rotor poles for ironless stator axial flux permanent magnet (AFPM) machine. The slot-pole combination is a vital aspect of optimization design for the improvement of torque and power density. This paper is mainly aimed...

The Halbach‐array permanent magnet (PM) rotors can achieve higher air‐gap flux density due to magnetic flux gathering effect, which contributes to the higher‐torque density improvement of the ironless stator axial flux PM (AFPM) machine. However, the end leakage fluxes of the ironless stator AFPM machine are serious due to the large magnetic resist...

In this paper, a high-speed Halbach-array PM rotor for ironless stator axial-flux permanent magnet (AFPM) machine is proposed and researched with consideration of the multi-physics constraints, including the electromagnetic characteristics, mechanical strength and rotor dynamics. Considering the severity of attractive force between twin rotors, the...

As rotor position sensors, the variable reluctance (VR) resolvers are playing critical roles in the industrial electric machine drivers. The VR resolvers have a simple structure, therefore they are reliable and durable under rough operation scenarios. However, the dedicated decoding system requires the voltage signal injection with high-frequency (...

With the development of aviation electrification, higher demands for electrical machines are put forward in aircraft electric propulsion systems. The aircraft electric propulsion requirements and propulsion motor features are analyzed in this paper. Comparing with conventional PM machines, ironless stator axial flux permanent magnet (AFPM) machine...

In this paper, a new hybrid excitation synchronous machine (HESM) with dual-end built-in field windings is designed for electric vehicle traction applications with consideration of electromagnetic performance. This HESM topology inherits the features of brushless HESMs with magnetic shunting rotor and benefits from better space utilization. The fun...

This paper presents integrated design and analysis of a new axial-flux permanent magnet (AFPM) machine, which consists of an ironless stator with double-layer concentrated non-overlapping windings and twin external rotors with Halbach-array PMs. A general sizing equation based on fundamental theory, easily adjustable for ironless stator AFPM machin...

Fractional-slot concentrated-winding (FSCW) permanent magnet synchronous machines, which are characterised with high power density, fault tolerance and wide constant-power speed range, are gaining more and more attention in the aircraft starter generator (SG) systems. Nevertheless, the short-circuit (SC) fault, especially the turn-to-turn SC fault,...

The doubly salient brushless DC generator (DSBLDCG), which is constituted of a doubly salient electro-magnetic machine with concentrated field magnetomotive forces (DSEM-CF) and the associated uncontrolled rectifier circuit has the characteristics of convenient voltage regulation and high reliability. However, the machine suffers from the inherent...

In this paper, the electromagnetic torque (EM) performance analysis of a parallel hybrid excitation machine (PHEM) is investigated. It is composed of a permanent magnet (PM) part and variable reluctance part. The flux paths of the two parts are independent and the armature windings are connected in series. PHEM is an axial parallel coupling of two...

More Electrical Aircraft (MEA) which replaces the hydraulic and pneumatic power by electrical power leads to reducing emissions and fuel consumption. The MEA concept has led to a growing use of the starter/generator (S/G) system. Permanent magnet (PM) machines have been gaining interests for aircraft S/G system application over the last few years....

In this paper, a novel modeling method for hybrid excitation synchronous machines (HESMs) with radial/axial flux paths via magnetic equivalent circuit (MEC) is proposed. 3D finite-element analysis (FEA) is essential when analyzing a machine with radial/axial flux paths due to the asymmetry in the axial direction. However, 3D FEA is computationally...

Concentrated windings permanent magnet machines are becoming a promising choice in aircraft generator application due to their advantages of compact structure, small short-circuit current and high power density. In this paper, the concentrated-windings permanent magnet synchronous machines (CW-PMSM) with four different types of rotor structure are...

The PM parts and electrical excitation part synchronously contribute to the output torque for the parallel hybrid excitation machine (PHEM), which consists of the permanent magnet synchronous machine (PMSM) and the doubly salient electro-magnet machine (DSEM). In this paper, the torque-angle characteristic of the presented machine is analyzed by fi...

This paper presents a new topology of parallel hybrid excitation machine (PHEM), which integrates permanent-magnet synchronous motor (PMSM) and variable-reluctance machine, namely, doubly salient electromagnetic machine (DSEM), and provides a solution to better field-regulating capability. The configuration and the operation principle of the propos...

This paper presents a new topology of parallel hybrid excitation brushless dc machine (PHE-BLDCM). Configuration and operational principles of the proposed PHE-BLDCM are introduced. The proposed PHE-BLDCM which can be used as the generator for aero-power system combines the merits of the permanent magnet synchronous machine and the doubly salient e...